A fuel cell system generally includes a fuel cell and tubes for reactive gases and accessories such as pumps and valves, which are to be connected to the fuel cell, and is mounted on a limited space, such as a vehicle. The technology of integrating part of the system or the whole system with the fuel cell (unitization) for size reduction has been proposed to improve the mountability of the fuel cell system (e.g., PTL1).
In the structure of unitizing part of the fuel cell system to improve the mountability of the fuel cell system, it is desirable to improve the convenience of attachment of the unitized tubes and accessories to the fuel cell. In the structure of unitizing part of the fuel cell system, it is also desirable to prevent reduction of the supply efficiencies of the reactive gases to the fuel cell, reduction of the discharge efficiency of drainage water from the fuel cell and reduction of the overall efficiency of the fuel cell system. Additionally, in the structure of utilizing part of the fuel cell system to the concentrated arrangement of the fuel cell, the tubes and the accessories, it is desirable to prevent the fuel cell from being affected by a damage of any of such tubes and accessories. There has been no sufficient measure to satisfy such requirements.